Isolation valves

ABSTRACT

Isolation valves for selectively sealing a first region from a second region. A gate valve can include a housing which defines a channel between the first and second regions. The valve includes a gate, located in the housing, and displaceable between a stowed position and a deployed position. When the gate is in the stowed position, communication is permitted between the first and second regions. When the gate is in the deployed position, the gate spans the channel and can be controlled to isolate the first and second regions. The valves can be used, for example, in connection with systems for processing large glass substrates. The valves are particularly useful for isolating long rectangular openings, such as the openings in substrate processing chambers. Isolating processing chambers or load lock chambers from one another, for example, in a linear system, is facilitated.

BACKGROUND

[0001] The present invention relates generally to substrate processingsystems, and, in particular, to isolation valves for substrateprocessing systems.

[0002] Glass substrates are being used for applications such as activematrix television and computer displays, among others. Each glasssubstrate can form multiple display monitors each of which contains morethan a million thin film transistors.

[0003] The processing of large glass substrates often involves theperformance of multiple sequential steps, including, for example, theperformance of chemical vapor deposition (CVD) processes, physical vapordeposition (PVD) processes, or etch processes. Systems for processingglass substrates can include one or more process chambers for performingthose processes.

[0004] The glass substrates can have dimensions, for example, of 550 mmby 650 mm. The trend is toward even larger substrate sizes, such as 650mm by 830 mm and larger, to allow more displays to be formed on thesubstrate or to allow larger displays to be produced. The larger sizesplace even greater demands on the capabilities of the processingsystems.

[0005] Some of the basic processing techniques for depositing thin filmson the large glass substrates are generally similar to those used, forexample, in the processing of semiconductor wafers. Despite some of thesimilarities, however, a number of difficulties have been encountered inthe processing of large glass substrates that cannot be overcome in apractical way and cost effectively by using techniques currentlyemployed for semiconductor wafers and smaller glass substrates.

[0006] For example, efficient production line processing requires rapidmovement of the glass substrates from one work station to another, andbetween vacuum environments and atmospheric environments. The large sizeand shape of the glass substrates makes it difficult to transfer themfrom one position in the processing system to another. As a result,cluster tools suitable for vacuum processing of semiconductor wafers andsmaller glass substrates, such as substrates up to 550 mm by 650 mm, arenot well suited for the similar processing of larger glass substrates,such as 650 mm by 830 mm and above. Moreover, cluster tools require arelatively large floor space.

[0007] Similarly, chamber configurations designed for the processing ofrelatively small semiconductor wafers are not particularly suited forthe processing of these larger glass substrates. The chambers mustinclude apertures of sufficient size to permit the large substrates toenter or exit the chamber. Moreover, processing substrates in theprocess chambers typically must be performed in a vacuum or under lowpressure. Movement of glass substrates between processing chambers,thus, requires the use of valve mechanisms which are capable of closingthe especially wide apertures to provide vacuum-tight seals and whichalso must minimize contamination.

[0008] Furthermore, relatively few defects can cause an entire monitorformed on the substrate to be rejected. Therefore, reducing theoccurrence of defects in the glass substrate when it is transferred fromone position to another is critical. Similarly, misalignment of thesubstrate as it is transferred and positioned within the processingsystem can cause the process uniformity to be compromised to the extentthat one edge of the glass substrate is electrically non-functional oncethe glass has been formed into a display. If the misalignment is severeenough, it even may cause the substrate to strike structures and breakinside the vacuum chamber.

[0009] Other problems associated with the processing of large glasssubstrates arise due to their unique thermal properties. For example,the relatively low thermal conductivity of glass makes it more difficultto heat or cool the substrate uniformly. In particular, thermal lossesnear the edges of any large area, thin substrate tend to be greater thannear the center of the substrate, resulting in a non-uniform temperaturegradient across the substrate. The thermal properties of the glasssubstrate combined with its size, therefore, makes it more difficult toobtain uniform characteristics for the electronic components formed ondifferent portions of the surface of a processed substrate. Moreover,heating or cooling the substrates quickly and uniformly is moredifficult as a consequence of its poor thermal conductivity, therebyreducing the ability of the system to achieve a high throughput.

[0010] In the past, a variety of isolation valves have been used toisolate two regions from one another. In an exemplary construction, agate slides into and out of a path, transversely to the path, to openand close the valve. With the gate in a closed position, a seal can beformed between the gate and a valve seat to prevent flow through thevalve. Slide valves offer particular compactness, in other words, asmall size as measured in a direction along the flow path.

[0011] One recently proposed system for processing large glasssubstrates is a modular in-line processing system, such as the systemdescribed in the previously mentioned U.S. patent application Ser. No.08/946,922. Such a system can be used for CVD or other thermal substrateprocessing and can include multiple back-to-back processing chambersthrough which a substrate is transferred. The process chambers typicallyare operated under vacuum or under very low pressure. Thus, there is arelatively uniform pressure distribution between the chambers which isinsufficient by itself to provide the required tight seal between thegate and the valve seat.

SUMMARY

[0012] In general, the invention discloses various improved isolationvalves. According to one aspect, an isolation valve for selectivelysealing a first region from a second region includes a housing. Thehousing defines a channel between the first region and the secondregion, and the channel extends at least between a first port and asecond port. The valve also includes a gate disposed within the housing.The gate is displaceable between a stowed position in whichcommunication is permitted between the first region and the secondregion, and a deployed position in which the gate spans the channel.

[0013] The gate includes first and second sealing members, each of whichhas a respective outward-facing surface. Further, the gate has anexpandable member disposed between the first sealing member and thesecond sealing member, wherein the expandable member is expandable froma first condition to a second condition and can be contracted from thesecond condition to the first condition.

[0014] In the first condition, the gate is moveable between the stowedand deployed positions. In the second condition, with the gate in thedeployed position, the first and second sealing members are biased apartfrom each other by expansion of the expandable member so that theoutward-facing surface of the first sealing member is sealingly engagedto the first port so as to seal the first region from the second region.The outward-facing surface of the second sealing member is engaged tothe housing.

[0015] In some implementations, such as where two or more processingchambers are positioned back-to-back, both sealing members engage theirrespective ports to seal the first region from the second region.

[0016] In various implementations, the expandable member can include abellows or an inflatable member, such as an elastomeric bladder.

[0017] In another aspect, an isolation valve includes a housing defininga channel between a first chamber and a second chamber and a gateassembly disposed within the housing. The valve also includes means forpositioning the gate assembly between a first port in communication withthe first chamber and a second port in communication with the secondchamber. Additionally, the valve has means for causing the gate assemblyto engage the first port so as initially to seal the first chamber fromthe second chamber. Furthermore, the valve has means for altering apressure within the housing to further seal the first chamber from thesecond chamber. A method of sealing a first chamber from a secondchamber also is disclosed.

[0018] In an alternative embodiment, an isolation valve includes ahousing having a passageway through which a substrate can betransferred. A surface along a perimeter of the passageway forms a seatfor engaging a gate. The valve also includes a gate disposed within thehousing, wherein the gate has a first position in which the passagewayis open and a second position in which the gate engages the seat to sealthe passageway. The valve also has a lift mechanism coupled to the gatefor controlling movement of the gate between its first position and anintermediate position opposite the passageway. The valve also includes arotating mechanism coupled to the gate for controlling movement of thegate between its intermediate position and its second position.

[0019] When the gate is in its second position, a horizontal forcecomponent can be provided to seal the gate against the passageway. Inone implementation, the rotating mechanism includes one or more pushcylinders each having respective first and second positions. Movement ofthe push cylinders between their first and second positions causes thegate to rotate between its intermediate raised position and its secondposition in which the passageway is sealed.

[0020] In various implementations, two or more substrate processingchambers can be positioned back-to-back. A double-sealing isolationvalve or independently controllable isolation valves can be providedbetween the chambers to seal them, for example, during processing.

[0021] The valve housings can be formed separately from the chambers andsubsequently secured in place. Alternatively, the valve housings can beformed as a single integral unit with a chamber.

[0022] Among the advantages of a valve according to the presentinvention is design flexibility. For example, in the laboratory orindustrial setting, the valve can be used as a door or gate throughwhich glass substrates or other items may pass. In such situations, itis advantageous to select a valve geometry (size, cross-sectionalprofile, etc.) to accommodate the items passing through the valve aswell as any other environmental factors. This is preferable to having toconform the items or processes by which they are manipulated togeometries and sizes of available valves.

[0023] By way of example, in the manufacture and processing of flatobjects such as glass substrates for flat panel displays, processingchambers may be used which have a relatively low profile, in otherwords, a small height and large width. Space efficiency considerationsindicate that the valves sealing such chambers need only have asimilarly low profile to accommodate the ingress and egress of theitems.

[0024] The use of an inflatable member to separate the valve plates canprovide a more even distribution of the sealing force between the valveplates than in a purely mechanical system. Thus, in the case of anelongated gate, the sealing force can be distributed substantiallycontinuously along the gate. However, whatever the desired gate profile,an appropriate inflatable chamber can be configured easily and can usestock inflation equipment. This feature provides cost savings byreducing the need for multiple complex mechanical linkages specificallyconfigured for each gate profile.

[0025] Another advantage is the ability to accommodate the valve to lessthan perfect valve seats. The inflatable member has significantflexibility and, therefore, can create an adequate seal despite a lossof parallelism, changes in seat separation, or even loss of flatness.With a mechanically-actuated valve, wear or contamination of the seatingsurfaces may greatly alter the forces applied to the plates. With theinflation member, the force is simply related to the pressure applied tothe chamber. Performance is less sensitive to wear except in the extremecase of a rupture or leak.

[0026] Additionally, to compensate for the lack of ability of thecamming mechanism to accommodate changes or irregularities in the seatsand to accommodate for the effect of wear of the camming mechanism, ahighly compressible flexible seal may be utilized with a cam-type valve.Such a seal will necessarily undergo a relatively high deformation andtherefore may be subject to wear or failure. With the present invention,the chamber can provide a significant degree of compliance so that thesame compliance need not be present in the seals. Therefore, the sealsare subjected to less deformation. The wearing of the mechanicallinkages also can create contaminant particles which can interfere withthe operation of the valve or the operation of any enclosure the valveis used to seal and contaminate any fluid passing through the valve.

[0027] In alternative implementations, mechanical isolation valves aredisclosed that are particularly suited for modular systems in whichmultiple chambers are aligned adjacent one another. Each chamber can beprovided with passageways at opposite sides of the chamber. Thepassageways, which can be used for transferring a substrate into or outof the chamber, can be opened or sealed by respective gates which arecontrolled independently of one another, thereby providing additionalflexibility. The mechanical isolation valves are compact and have arelatively simple construction, thereby helping to reduce manufacturingcosts.

[0028] The mechanical valves also can provide an improved means forsealing one chamber from another chamber and help preventcross-contamination from process gases used in the various chambers. Themechanical rotation of the gate toward the passageway creates the sealand provides lateral pressure to improve the seal that is required whenprocessing glass substrates.

[0029] When two chambers are aligned adjacent one another, the areabetween the chambers can be isolated from either one or both of thechamber interiors effectively forming a buffer chamber. The area betweenthe chambers can, therefore, be protected, for example, from processgases, some of which may be corrosive. By isolating the area between thechambers from the chamber interiors, other components of the systemexternal to the processing chambers can be protected from contact withcorrosive gases or other harmful materials used within the chambersduring substrate processing. Additionally, the pressure of the areabetween the chambers can be controlled independently of the pressures ineither one or both of the chamber interiors.

[0030] Other features and advantages will be apparent from the detaileddescription, drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]FIG. 1 is a transverse cross-sectional view of a valve, shown inan open configuration, according to one implementation of the invention.

[0032]FIG. 2 is a partial longitudinal cross-sectional view of the valveof FIG. 1, taken along line 2-2.

[0033]FIG. 3 is a top cross-sectional view of the valve of FIG. 2, takenalong line 3-3.

[0034]FIG. 4 is a transverse cross-sectional view of the valve of FIG.1, shown in a closed configuration.

[0035]FIG. 5 is a partial longitudinal cross-sectional view of the valveof FIG. 4, taken along line 5-5.

[0036]FIGS. 6 and 7 are partial transverse cross-sectional views ofvalves according additional implementations of the invention.

[0037]FIG. 8 is a partial elevated view of a chamber according to yetanother implementation of the invention.

[0038]FIG. 9 is a side view of the chamber of FIG. 8 with actuatorhousings.

[0039]FIG. 10 is a side view of the chamber of FIG. 8 showing a liftmechanism in a lowered position.

[0040]FIG. 11 illustrates a rod block which forms part of the liftmechanism in FIG. 10.

[0041]FIG. 12 is a side view of the chamber of FIG. 8 showing the liftmechanism in a raised position.

[0042]FIG. 13 is a side view of the lift mechanism taken along line13-13 in FIG. 12.

[0043]FIG. 14 is a side view of the lift mechanism taken along line14-14 in FIG. 12.

[0044] FIGS. 15A-15C illustrate the sealing plate between a loweredposition, a raised position and a closed position, respectively.

[0045] FIGS. 16-17 are partial elevated side views of the chamber ofFIG. 8 with a sealing plate positioned in lowered and raised (or closed)positions, respectively.

[0046]FIG. 18 is a partial elevated side view of the chamber of FIG. 16including a drive mechanism for a substrate transfer shuttle.

[0047]FIG. 19 illustrates two chambers positioned adjacent one anotheraccording to the invention.

DETAILED DESCRIPTION

[0048] As shown in FIGS. 1 and 2, a valve 10 includes a housing 12, agate 14 and an actuator 16. The housing 12 has an interior bounded byfirst and second vertically-extending sides 18A and 18B, a top 20, abottom 22, and ends 24A, 24B. In general, the valve can be used, forexample, to isolate one process chamber from another process chamber, orto isolate different regions from one another.

[0049] The housing defines a passageway 28 which extends along a paththrough the housing from an inlet 30 to an outlet 32. In variousimplementations, the roles of the inlet 30 and outlet 32 can be reversedsuch that a substrate can travel in either direction through the valve.The channel has a longitudinal axis 200. The inlet 30 and outlet 32extend transverse to the axis 200 and are elongate and generallyrectangular in shape. First and second regions or chambers 202, 204 arelocated adjacent the inlet 30 and outlet 32, respectively. An externalregion is shown generally as 206. In the exemplary embodiment, thehousing 12 is generally symmetric about a vertical transverse centerplane 208.

[0050] With the valve in an open condition, as shown in FIGS. 1 and 2,the gate 14 is in a lowered or stowed position, residing in a bay 34 ofthe housing. The gate 14 has first and second sealing members, such assealing plates 36A, 36B, respectively (FIG. 2). Each sealing plate 36A,36B has a longitudinally outboard plate 38A, 38B, and a longitudinallyinboard plate 40A, 40B. Each outboard plate 38A, 38B is held flatagainst the associated inboard plate 40A, 40B such as by means ofcounter-bored screws 42. The outboard faces 44A, 44B of outboard plates38A, 38B face the regions 202, 204, respectively, and each bears agenerally rectangular slot in which a gasket 48A, 48B is carried. Theinboard faces 46A, 46B of inboard plates 40A, 403 face toward theregions 204, 202, respectively, and form inboard faces of the sealingplates 36A, 36B, respectively.

[0051] Flexures or leaf springs 50A, 50B depend from the lower edges ofthe sealing plates 36A, 36B, respectively. Each flexure 50A, 50B isattached at its upper edge 52A, 52B to the lower edge of the associatedinboard plate 40A, 40B. The bottom end 54A, 54B of each flexure 50A, 50Bis secured to a transversely-extending cross-member 60 of a frame 62(FIG. 1).

[0052] The frame 62 further includes a pair of posts or uprights 64A,64B (FIG. 1) extending upwardly from the cross-member 60 at oppositeends of the cross-member. Extending along the laterally outboard facesof the uprights 64A and 64B, respectively, are a pair of outwardlyfacing channel members 66A, 66B. The channel members are of openrectangular section.

[0053] At opposite sides of the housing, pairs of upper and lower lowfriction guides 68A, 68B extend inwardly from respective sides 18A, 18B.The guides are accommodated within the associated channel members 66A,66B so as to allow the channel members and gate 14 to slide verticallybetween the open position shown in FIGS. 1 and 2 and a closed positionshown in FIGS. 4 and 5.

[0054] Referring to FIG. 3, an expandable chamber or volume 80 which canbe inflated is disposed within the housing. The chamber 80 is bounded byan expandable member, such as an inflatable elastomeric bladder 82 or abellows, which is positioned between the sealing plates 36A and 36B. Inthe illustrated embodiment, the bladder 82 is continuous andsubstantially laterally coextensive with the sealing plates 36A, 36B,being slightly recessed from upper, lower and lateral edges of theplates. The bladder has an inner surface 84 surrounding the chamber 80and an outer surface 86 which engages the inboard faces 46A, 46B of thesealing plates.

[0055] On each side of the gate 14, center blocks 90A, 90B (see alsoFIG. 1) are rigidly affixed to the associated uprights 64A, 64B andextend laterally inward slightly beyond the lateral edges of the sealingplates 36A and 36B. Contact between the inboard faces 46A, 46B of thesealing plates 36A, 36B and the adjacent sides 92A, 92B of the blocksrestricts inward longitudinal movement of the sealing plates.

[0056] Above and below each center block 90A, 90B is a centeringmechanism 100 (FIGS. 1 and 3). Each centering mechanism 100 includes afirst pin 104A (FIG. 3) extending laterally outward from the associatedside of the sealing plate 36A and a second pin 104B extending laterallyoutward from the associated side of the sealing plate 36B. A coil-typetension spring 106 connects the first pin 104A to the second pin 104B.Thus, collectively, the springs 106 of the centering mechanisms 100 biasthe two sealing plates 36A, 36B toward each other and, thus, toward thetransverse vertical center plane 208.

[0057] In an alternate embodiment shown in FIG. 6, each centeringmechanism comprises a center pin 102 extending laterally inward from anassociated upright 64A, 64B. An upstream coil-type tension spring 106Aconnects the first pin 104A to the center pin 102, and a downstreamcoil-type tension spring 106B connects the second pin 104B to the centerpin 102. The springs 106A, 106B bias the sealing plates 36A, 36B towardthe transverse vertical center plane 208.

[0058] Returning to FIG. 3, an inflation/deflation conduit 110 extendsthrough the bladder 82 into the chamber 80. The conduit 110 can bedirected between the flexures 50A, 50B and out through the actuator 16to a remote source 112 (FIG. 1). In the exemplary embodiment, the source112 can take the form of an appropriate pump along with the associatedvalves and control systems for selectively introducing a gas into thechamber 80 through the conduit 110 and withdrawing the gas from thechamber through the conduit 110 to inflate and deflate the chamber. Aconduit 114 (FIG. 1) extends through the housing into the cavity 34. Theconduit 114 is connected to a source 116 which may be similar to asource 112. The source 116 facilitates the selective pressurization anddepressurization of the housing external to the chamber 80.

[0059] To close the valve, the actuator 16 is controlled to raise thegate 14 from the lowered or stowed position (FIGS. 1 and 2) to a raisedor deployed position (FIGS. 4 and 5). In the deployed position, thesealing plates 36A, 36B are aligned with and facing the inlet and outletports 30, 32, respectively. Valve seats 120A, 120B are formed in thehousing surrounding the inlet and outlet ports 30, 32, respectively. Thevalve seats have seating faces 122A, 122B facing generally toward theregions 204, 202, respectively. The seating faces 122A, 122Brespectively face and are aligned with the gaskets 48A, 48B when thegate 14 is in the deployed position.

[0060] With the gate 14 in the deployed position, the chamber 80 isinflated or pressurized, producing longitudinal outward forces on thesealing plates 36A, 36B. When the pressure in the chamber 80 issufficient, it will overcome the tension in the springs 106 and drivethe sealing plates 36A, 36B longitudinally outward to place the gate 14in an expanded condition. The longitudinally outward movement of thesealing plates 36A, 36B brings the gaskets into sealing engagement withthe seating faces 122A and 122B, respectively (FIG. 5). In this way, thesealing plates 36A, 36B become sealingly engaged to the seats 122A, 122Bof the respective inlet and outlet ports 30, 32 to prevent fluid flowthrough the ports. In this manner, the regions or chambers 202, 204 canbe isolated from one another as well as from the passageway 28 in thevalve housing.

[0061] To open the valve, the chamber 80 is deflated or depressurized,reducing the longitudinally outward forces on the sealing plates 36A,36B. When the pressure in the chamber 80 is sufficiently reduced, thetension in the springs 106 overcomes the pressure difference across therespective plates 36A, 36B and overcomes any sticking of the gaskets48A, 48B so as to disengage the sealing plates and gaskets from theseats 122A, 122B. Although the chamber 80 can be depressurized byventing to atmosphere, a vacuum may be applied to the chamber by thesource 112 so that reduced pressure further assists the springs 106 todraw the plates together. With the chamber 80 returned to the unexpandedcondition, the actuator 16 is controlled to lower the gate 14 from thedeployed position to the stowed position, thereby clearing the channel28.

[0062] Exemplary materials used in construction of the valve 10 includealuminum for the housing 12 and the plates 36A, 36B, although stainlesssteel can be used if there is to be exposure to chemicals which reactwith aluminum. The gaskets 48 can be formed of a flouroelastomer such assold under the trademark VITON by E.I. du Pont de Nemours and Company.The gaskets 48 are secured in their associated grooves via bondingadhesive or via forming the grooves with a dovetail or similar profileto capture the gaskets. The flexures 50A, SOB can be formed of stainlesssteel sheets.

[0063] The dimensions of the valve 10 can be selected based on theparticular application in which it is to be used. An exemplaryapplication involves the sealing of chambers used in large glasssubstrate processing (e.g., separating a load lock chamber from aprocess chamber). For such an application the valve can be configured toaccommodate passage of substrates between the chambers. In an exemplaryembodiment suitable for large glass substrates, such as substrateshaving an area of one square meter, the ports 30, 32 are about 5-6inches high and about 50 inches wide. The plates 36A, 36B can beapproximately 1 inch greater in width and height than the ports 30, 32,and the bladder 82 approximately 0.5 inches greater in width and heightthan the ports.

[0064] When both plates are sealingly engaged to their respective ports,the pressure in the housing can be greater than the pressure in anadjacent processing chamber. The pressure in the housing can be atambient pressure.

[0065] Furthermore, the ability to pressurize and depressurize thehousing 12 external to the chamber 80 provides a number of options tothe user. With a pressure in the chamber 80 designated P₃ (controlledvia the source 112), and an ambient pressure designated P_(A), apressure P₄ in the housing can be controlled relative to any of P_(A),P₃, and pressures P₁ and P₂ in the regions 202 and 204, respectively. Inone option which is particularly useful when the difference between P₁and P₂ is large, the housing 12 and chamber 80 can be pressurizedsimultaneously. Since the strength of the bladder 82 limits the amountby which P₃ may exceed P₄, the more P₄ is increased, the more P₃ may beincreased so as to increase the sealing force. Furthermore, to theextent that the chamber 80 does not cover the entire area of the gate14, the force applied by the pressure P₄ to those areas of the gatebeyond the chamber will help seal the valve. This may be particularlyuseful where multiple discrete chambers, such as those formed by metalbellows are utilized. In a situation where the valve is used to seal alow pressure processing chamber from a higher pressure chamber orregion, it may be particularly desirable to prevent contamination. Insuch a situation, a vacuum can be applied to the housing 12 to reducethe pressure P₄ so that any gas leaking from the high pressure chambercan be evacuated through the conduit 114.

[0066]FIG. 7 shows an alternate valve having one sealing plate 36B′which generally is similar to the plates the 36A, 36B in FIGS. 1-6. Inan exemplary application, an inlet 30′ is coupled to a low pressurechamber which can be pressurized with inert gas. A second port 32′ canbe connected to a process chamber for low pressure processing in areactant gas environment. The inert gas can flow through holes 37 in theplate 36A′ to fill the.housing. The pressure from the inert gas canaugment the sealing in a similar fashion to the housing pressurizationdescribed above.

[0067] The use of an inflatable chamber 80 to separate the valve plates36A, 36B and seal the valve 10 provides a significant degree offlexibility in valve design. The force (pressure distribution)separating the plates 36A, 36B can be distributed more evenly than in apurely mechanical system. For example, the force can be distributedsubstantially continuously along an elongate gate member. Valves asdescribed and illustrated in FIGS. 1-7 can offer savings in cost,weight, size, and complexity.

[0068] Various modifications can be made to the implementationsdescribed above. For example, although in the illustrated embodiment thechamber 80 is formed by a generally rectangular continuous elastomericbladder 82, one or more bladders of other geometries may be used. Thechamber 80 can be formed other than by an elastomeric bladder, such asby one or more bellows. In general, the chamber 80 includes anexpandable member which can be expanded from a first condition to asecond condition and which can be contracted from the second conditionto the first condition. In the first condition, the gate is moveablebetween the stowed and deployed positions, and in the second condition,with the gate in the deployed position, the first and second sealingmembers are biased apart from each other by expansion of the expandablemember so that the outward-facing surface of at least one sealing memberis sealingly engaged to a respective one of the ports so as to seal thefirst region from the second region.

[0069] Additionally, although the valve illustrated in FIGS. 1-6 issubstantially symmetric about its transverse central plane, asymmetricvalves also can be provided. Various actuators and gate geometries maybe used and many specific properties of the valve may be influenced ordictated by the particular application for which the valve is designatedor adapted.

[0070] In the implementations described above with respect to FIGS. 1-6,the sealing plates 36A, 36B are controlled substantially simultaneouslyto engage their respective seats 122A, 122B and to isolate the regions202, 204.

[0071] In contrast to the foregoing description, as an alternativeembodiment, FIGS. 8-19 illustrate a substrate chamber with mechanicalisolation valves. The implementations described below allow passagewaysin adjacent chambers to be sealed independently of one another.Moreover, the valves described below include mechanically actuated gateswhich provide a horizontal force component to enhance the seal betweenthe gate and the valve seat.

[0072] Referring to FIGS. 8-9, a chamber 300, such as a chemical vapordeposition (CVD) or other substrate processing chamber, includes a frame302, having sidewalls 301A-301D, a top 303A and a bottom 303B. The valvehousings 304A, 304B are integrally formed with the sidewalls 301A, 301Bof the chamber 300 so that the valve housings and the chamber form asingle unit. The valve housings also can be formed separately and thenbolted or otherwise attached to the chamber. As discussed in greaterdetail below, the valve housing 304B is wider than the valve housing304A in a direction parallel to the chamber sidewalls 301C, 301D.

[0073] An opening or passageway 312B is formed in the sidewall 301B ofthe chamber 300. Another opening or passageway 312A is formed in theopposite sidewall 301A. The dimensions of the passageways 312A, 312B canbe selected to allow a substrate to be transferred in and out of thechamber 300 through the passageways. An outward-facing surface along theperimeter of the passageway 312B forms a seat 314B for engaging anassociated gate 310B, and a similar seat is formed by an outward-facingsurface along the perimeter of the passageway 312A to engage anassociated gate 310A. The respective surfaces that form the seats, suchas the seat 314B, face away from the interior of the chamber 348. Thegates 310A, 310B can be formed as sealing plates. In one implementation,the sealing plates 310A, 310B have a length of approximately 50 inches,and a height of approximately 5-6 inches. Such an implementation issuitable for large glass substrates on the order, for example, of onesquare meter. Each valve housing 304A, 304B has an open side oppositethe, respective passageways 312A, 312B.

[0074] Reinforcement members 316A, 316B can be provided above the valvehousings 304A, 304B to reinforce the chamber frame 302. Respectiveactuator housings, or frames, 306A, 306B are bolted or otherwise securedto the chamber 300 below the valve housings 304A, 304B. The actuatorhousings 306A, 306B provide stiffness for the chamber 300. The actuatorhousing 306A and the valve housing 304A are configured so that theactuator housing extends slightly beyond the valve housing in adirection parallel to the sidewalls 301C, 301D and away from the chamberinterior 348. Similarly, the actuator housing 306B and the valve housing304B are configured so that the valve housing extends slightly beyondthe actuator housing in a direction parallel to the sidewalls 301C, 301Dand extending away from the chamber interior 348. Such an asymmetricconfiguration allows multiple chambers to be aligned adjacent oneanother as discussed further below with respect to FIG. 19.

[0075] Each actuator housing 306A, 306B contains a respective actuator307A, 307B. Each actuator 307A, 307B includes a respective liftmechanism 308A, 308B for lifting and lowering an associated one of thegates 310A, 310B disposed within the valve housings.304A, 304B. Eachactuator housing 307A, 307B also includes a respective rotatingmechanism 309A, 309B coupled to an associated one of the lift mechanisms308A, 308B, as well as coupled to as associated one of the gates 310A,310B.

[0076] Each lift mechanism 308A, 308B can be raised from a first loweredposition to an intermediate or raised position. The lift mechanisms308A, 308B also can be rotated from the intermediate raised position toa second closed position by actuating the associated rotating mechanism309A, 309B. In the closed position, the gates 310A, 310B engage theirrespective seats 314A, 314B and seal the chamber 300 from the valvehousings 304A, 304B. When the gate is in its second closed position, ahorizontal force component is provided to seal the gate against thepassageway.

[0077] The lift mechanisms 308A, 308B also can be returned to theirrespective lower positions. Moreover, the lift mechanisms 308A, 308B canbe controlled independently of one another. As shown in FIG. 9, the liftmechanism 308B is in the first (lowered) position, and the gate 310Bdoes not engage its seat. The lift mechanism 308A, however, is shown inits raised position with the rotating mechanism 309A actuated so thatthe gate 310A engages the seat 314A (FIG. 8) and seals the chamber 300from the housing 304A.

[0078] Referring to FIG. 10, each lift mechanism, such as the liftmechanism 308B, includes a central lift cylinder 318 mounted to a pivotplate 328. The lift cylinder 318, which has a piston rod 319 extendingvertically through its major axis, is coupled to a lift plate 320. Thelift plate 320 includes substantially horizontal sections 321 thatextend laterally outward. A respective rod block 322 is coupled to thelift plate 320 at each of its laterally extending ends 321. Each rodblock 322 has multiple cam followers or wheels 324 which allow the rodblock 322 to slide vertically up or down along stationary vertical slots326 disposed within the housing 306B. The lower section of each rodblock 322 includes a vertical slot 340 (FIG. 10) whose function isexplained below.

[0079] As shown in FIGS. 10-11, each rod block 322 carries a verticalshaft 330, the lower end of which extends at least partially into therod block 322 in a fixed position and is substantially parallel to themajor axis of the rod block 322. The upper end of each shaft 330 extendsthrough a respective compressible bellows 332 and is coupled at itsupper end to the gate 310B (not shown in FIG. 10). The bellows 332 helpmaintain the pressure or vacuum as the shafts 330 are moved upward ordownward. The gate or sealing plate 310B is offset slightly with respectto the vertical axis 331 of the shaft 330 (FIG. 15A). A sphericalalignment joint 358 (FIG. 19) helps provide the desired alignmentbetween the sealing plate 310B and the seat 314B. In the illustratedimplementation, the sealing plate 310B and the vertical axis 331 of theshaft 330 form an angle x of at least 0.5 degrees, for example,approximately 1.3 degrees (FIG. 15A). In some implementations, however,the angle x can be less than 0.5 degrees yet greater than 0 degrees.

[0080] In one implementation, the rotating mechanism 309B includes atleast one push cylinder 334 coupled to a push plate 336 by spherical rodends 342 (see FIGS. 10, 12 and 14). The illustrated implementationincludes a pair of push cylinders 334. Distal ends of the push plate 336are coupled to low friction cam followers or wheels 338. To maintain thedesired orientation of the push plate, the push plate 336 is coupled toa total of three cam followers 338. When the rod blocks 322 are movedvertically upward or downward, the vertical slot 340 disposed within thelower section of each rod block 322 slides along the cam followers 338which remain substantially stationary.

[0081] When the lift cylinder 318 is in its first or lowered position(FIGS. 10 and 15A), the sealing plate 310B is positioned slightly lowerthan the passageway 312B between the interior 348 of the chamber 300 andthe valve housing 304B (FIG. 15A). In this first lowered position, thetop of the sealing plate 310B is displaced slightly outward from thelower portion of the seat 314B. As noted above, in the illustratedimplementation, the sealing plate 310B is onset slightly from thevertical axis 331 of the shaft 330 as well as from the vertical axis 313of the seat 314B.

[0082] The lift cylinder 318 can be controlled to move the sealing plate310B from the lower position to the raised intermediate positionopposite the passageway 312B to the chamber 300. In particular, the liftcylinder 318 causes the piston rod 319 to move vertically upward (FIGS.12-13). Upward movement of the piston rod 319 lifts the entire liftplate 320 and the attached rod blocks 322 upward. Upward movement of therod blocks 322 lifts the shafts 330 upward, thereby moving the sealingplate 310B to the raised position opposite the passageway 312B (FIG.15B). In this intermediate raised position, the sealing plate 310B isnot yet sealed against the seat 314B, and the top of the sealing platetilts away from the passageway 312B.

[0083] To seal or close the passageway 312B, air pressure in the pushcylinders 334 is reversed to move the push cylinders from respectivefirst or extended positions to respective second or contractedpositions. As the cylinders 334 move to their contracted positions, thepush plate 336 moves slightly outward away from the chamber 300. Thelateral outward movement of the push plate 336 causes the lift plate320, the rod blocks 322 and the shafts 330 to rotate slightly so thatthe sealing plate 310B is moved flush against the seat 314B surroundingthe passageway 312B (FIG. 15C). Specifically, in the illustratedimplementation, the sealing plate 310B is rotated approximately 1.3degrees, thereby moving the sealing plate to its second or closedposition and sealing the chamber passageway 312B. When the sealing plate310B is flush against the seat 314B, fluid communication between thechamber interior 348 and the interior of the valve housing is preventedthrough the passageway 312B.

[0084] To unseal or open the passageway 312B and move the sealing plate310B to its lowered position, the procedure described above is reversed.The air pressure in the push cylinders 334 again is reversed to move thepush cylinders to their respective extended positions. In someimplementations, the pressure of the push cylinders 334 is changedsubstantially simultaneously. In other implementations, particularlywhen the seal created between the sealing plate 310B and the seat 314Bis tight, the pressure of one push cylinder 334 can be changed prior tochanging the pressure of the other push cylinder. As the seal isloosened, the sealing plate 310B rotates back to its raised intermediateposition in which the sealing plate is opposite, but not in contactwith, the seat 314B (FIG. 15B). The lift cylinder 318 then can becontrolled to bring the sealing plate 310B to its lower position inwhich the top of the sealing plate 310B is opposite the lower portion orbottom of the seat 314B (FIG. 15A). In other words, the top of thesealing plate 310B can be substantially at least as low as the bottom ofthe passageway 312B. The sealing plate 310B remains disposed within thevalve housing 304B even when the sealing plate is in the lower position(FIG. 16).

[0085] The sealing plate 310A and the actuator 307A operate insubstantially the same manner as the sealing plate 310B and the actuator307B.

[0086] In some implementations, the sealing plate 310B need not be onsetfrom the vertical axis 331 of the associated shaft 330. Rather, thesealing plate 310B and the associated shaft 330 can be substantiallyparallel to one another. In such an implementation, when the liftmechanism 308B is in its lowered position, the sealing plate 310B, aswell as the associated shaft 330, is slightly offset from the verticalaxis of the 313 of the seat 314B such that the top of the sealing platetilts away from the seat. Once the lift mechanism 308B is moved to itsintermediate raised position, the push cylinders 334 cause the sealingplate 310B and the shaft to rotate so as to move the sealing plate toits closed position, thereby sealing the chamber passageway 312B. Whenthe gate 310B is in its closed position, the sealing plate 310B, theassociated shaft 330 and the vertical axis of the seat 314B aresubstantially parallel to one another.

[0087] Referring again to FIG. 8, each of the valve housings 304A, 304Bincludes openings 344 that are substantially perpendicular to thepassageways 312B, 312A in the interior 348 of the chamber 300. Theopenings 344 are configured such that when the sealing plate 310B (or310A) is in its raised position, the openings 344 in the valve housing304B are substantially parallel to the width of the sealing plate (FIG.17). The dimensions of the openings 344 are configured to be slightlylarger than a cross-section of the sealing plates 310A, 310B so that thesealing plates can be removed from their respective housings 304A, 304Bvia the openings for maintenance or inspection. The valve housings 304A,304B also have one or more openings 346 through their respective topsurfaces. The openings 346 aid visual inspection of alignment of thesealing plates 310A, 310B, as well as the removal of the sealing platesand other maintenance functions.

[0088] As noted above, the valve housing 304B is somewhat wider than thevalve housing 304A in a direction parallel to the chamber sidewalls301C, 301D. Referring to FIGS. 8 and 18, the valve housing 304B includesone or more openings 352 which serve as a vacuum feed through for adrive mechanism 350 of a substrate transfer shuttle or other substratetransfer mechanism (not shown) that transfers substrates between processchambers. In the illustrated implementation, the opening 352 is locatedadjacent one of the openings 344, and the drive mechanism 350 isdisposed within the valve housing 304B. Further details of an exemplarydrive mechanism 350 and substrate transfer shuttle are described in thepreviously mentioned U.S. application entitled “Method and Apparatus forSubstrate Transfer and Processing” [attorney docket 2519/US/AKT(05542/235001)]

[0089] As shown in FIG. 19, a first chamber 300′ and a second chamber300″, each of which has a construction similar to that of the chamber300, can be aligned to permit a substrate to be transferred from onechamber to the other and vice-versa. Features of the chambers 300′, 300″are designated with reference numerals which identify similarly-numberedfeatures of the chamber 300. Thus, the first chamber 300′ has aninterior 348′, a valve housing 304B′, and an actuator housing 306B′. Thevalve housing 304B′ includes an opening 352′ to serve as a feed throughfor the drive mechanism of a substrate shuttle transfer. As shown inFIG. 19, the sealing plate 310B′ is in its lowered position. Similarly,the second chamber 300″ has an interior 348″, a valve housing 304A″, andan actuator housing 306A″. As shown in FIG. 19, the sealing plate 310A″is in its raised position.

[0090] Due to the asymmetry between the respective valve housings 304B′,304A″ and the actuator frames 306B′, 306A″, the valve housing 304B′ ofthe first chamber 300′ partially extends over the actuator frame 306A″of the second chamber 300″ when the chambers are positioned adjacent oneanother and coupled to one another. The construction of the chambers300′, 300″ increases the ease with which two or more chambers can becoupled together as part of a modular system having multiple chambers.The chamber construction also increases the overall compactness of thesystem.

[0091] When both sealing plates 310B′, 310A″ are in their respectivelower positions, a substrate can be transferred from one chamber to theother. When both sealing plates 310B′, 310A″ are in their respectiveraised and sealed positions, the area between the two sealing plates isisolated from the interiors 348′, 348″ of the chambers 300′, 300″,electively forming a buffer chamber. The area between the sealing plates310B′, 310A″ is, therefore, protected, for example, from process gases,some of which may be corrosive. By isolating the area between thesealing plates from the interiors of the chambers, the drive mechanism350 associated with the substrate transfer shuttle can be protected fromcontact with corrosive gases or other harmful materials used within thechambers during substrate processing. Additionally, the pressure of thearea between the sealing plates 310B′, 310A″ can be controlledindependently of the pressures in the interiors 348′, 348″ of either orboth of the chambers 300′, 300″. For example, the pressure in the areabetween sealing plates 310B′, 310A″ can be controlled to increase theforce applied by the sealing plates 310B′, 310A″ against the respectiveseats 314B′, 314A″ to improve the seal created by the plates. Similarly,prior to unsealing the plates 310B′, 310A″, the pressure in the areabetween the plates can be controlled to make it easier to unseal themfrom their respective seats 314B′, 314A″.

[0092] Other implementations are within the scope of the followingclaims.

What is claimed is:
 1. An isolation valve for selectively sealing a first region from a second region, the isolation valve comprising: a housing defining a channel between the first region and the second region, the channel extending at least between a first port and a second port; and a gate disposed within the housing and displaceable between a stowed position in which communication is permitted between the first region and the second region, and a deployed position in which the gate spans the channel, the gate including: (a) first and second sealing members, each of which has a respective outward-facing surface; and (b) an expandable member disposed between the first sealing member and the second sealing member, wherein the expandable member is expandable from a first condition to a second condition and can be contracted from the second condition to the first condition, wherein, in the first condition, the gate is moveable between the stowed and deployed positions, and in the second condition, with the gate in the deployed position, the first and second sealing members are biased apart from each other by expansion of the expandable member so that the outward-facing surface of the first sealing member is sealingly engaged to the first port so as to seal the first region from the second region, and the outward-facing surface of the second sealing member is engaged to the housing.
 2. The valve of claim 1 wherein, with the gate in the deployed position and the expandable member in the second condition, the second sealing member is sealingly engaged to the second port so as to prevent communication through the second port.
 3. The valve of claim 1 wherein the first and second sealing members are substantially aligned with and parallel to each other.
 4. The valve of claim 1 wherein each of the first and second sealing members comprises a substantially flat plate.
 5. The valve of claim 1 wherein the expandable member comprises an inflatable member.
 6. The valve of claim 5 wherein the expandable member comprises an elastomeric bladder.
 7. The valve of claim 1 wherein the expandable member comprises a bellows.
 8. The valve of claim 1 wherein the outward-facing surface of the first sealing member includes a first gasket, and wherein the outward-facing surface of the second sealing member includes a second gasket.
 9. The valve of claim 1 wherein, with the valve in the deployed position and the expandable member in the second condition, fluid communication is not permitted between the second port and an interior of the housing.
 10. The valve of claim 1 wherein the housing further includes a bay, wherein the gate resides in the bay when the expandable member is in the first condition and the gate is in the stowed position.
 11. The valve of claim 1 further comprising at least one spring biasing the first and second sealing members toward each other.
 12. The valve of claim 11 comprising a plurality of pairs of tension springs, wherein a first spring in each pair couples the first sealing member to a frame, and a second spring in each pair couples the second sealing member to the frame, the first spring axially aligned with the second spring.
 13. The valve of claim 1 further comprising an actuator for selectively moving the gate between the stowed and deployed positions.
 14. The valve of claim 13 further comprising a frame coupling the actuator to the gate, the frame including: a transverse cross-member coupled to the actuator and having first and second ends; and first and second post members at the first and second ends of the cross-member, respectively, the first and second post members each coupled to the first and second sealing members.
 15. The valve of claim 14 further comprising first and second flexures, each of which has an upper edge and a lower edge, the lower edges of the flexures secured to the cross-member and the upper edge of the first flexure secured to the first sealing member and the upper edge of the second flexure secured to the second sealing member.
 16. The valve of claim 15 further comprising a first conduit for inflating the expandable member, the first conduit passing between the first and second flexures.
 17. The valve of claim 16 further including a second conduit for deflating the expandable member, wherein the second conduit passes between the first and second flexures.
 18. The valve of claim 1 wherein, with the gate in the deployed position and the expandable member in the second condition, the second sealing member is sealingly engaged to the second port so as to prevent communication through the second port, and a pressure in the housing is greater than a pressure in an adjacent processing chamber.
 19. The valve of claim 18 wherein the pressure in the housing is at an ambient pressure.
 20. The valve of claim 1 wherein, with the gate in the deployed position and the expandable member in the second condition, the second sealing member is sealingly engaged to the second port so as to prevent communication through the second port, and wherein the housing defines a cavity external to an area bounded by the expandable member with the cavity at a first pressure that is lower than a second pressure in the area bounded by the expandable member.
 21. An isolation valve comprising: a housing defining a channel between a first chamber and a second chamber; a gate assembly disposed within the housing; means for positioning the gate assembly between a first port in communication with the first chamber and a second port in communication with the second chamber; means for causing the gate assembly to engage the first port so as initially to seal the first chamber from the second chamber; and means for altering a pressure within the housing to further seal the first chamber from the second chamber.
 22. A method of sealing a first chamber from a second chamber by using a valve having a housing and a gate assembly configured to selectively isolate the first chamber from the second chamber, the method comprising: positioning the gate assembly between a first port in communication with the first chamber and a second port in communication with the second chamber; causing the gate assembly to engage the first port so as to initially seal the first chamber from the second chamber; and altering a pressure within the housing to further seal the first chamber from the second chamber.
 23. The method of claim 22 wherein altering the pressure includes raising such pressure above a pressure in the first chamber.
 24. The method of claim 22 wherein altering the pressure includes raising such pressure above an ambient pressure outside the chambers.
 25. The method of claim 22 wherein altering the pressure includes reducing such pressure below a pressure in the first chamber.
 26. An isolation valve comprising: a housing having a passageway through which a substrate can be transferred, wherein a surface along a perimeter of the passageway forms a seat for engaging a gate; a gate disposed within the housing, wherein the gate has a first position in which the passageway is open and a second position in which the gate engages the seat to seal the passageway; a lift mechanism coupled to the gate for controlling movement of the gate between its first position and an intermediate raised position opposite the passageway; and a rotating mechanism coupled to the gate for controlling rotation of the gate between its intermediate raised position and its second position.
 27. The valve of claim 26 wherein the rotating mechanism includes at least one push cylinder having respective first and second positions, wherein movement of the at least one push cylinder between its first and second positions causes the gate to rotate between its intermediate raised position and its second position.
 28. The valve of claim 26 wherein, when the gate is in its second position, a horizontal force component is provided to seal the gate against the passageway.
 29. The valve of claim 26 wherein the lift mechanism includes: a lift cylinder; a piston rod coupled to the lift cylinder; a lift plate coupled to the piston rod; and at least one shaft coupled at one end to the lift plate and coupled at a second end to the gate.
 30. The valve of claim 29 wherein the gate has a vertical axis offset slightly from a vertical axis of the at least one shaft.
 31. The valve of claim 30 wherein the vertical axis of the gate is offset by at least 0.5 degrees from the vertical axis of the at least one shaft such that a top of the gate tilts away from the passageway when the gate is in its intermediate raised position.
 32. The valve of claim 30 wherein, when the gate is in its first position, the top of the gate is substantially at least as low as a bottom of the passageway.
 33. The valve of claim 26 wherein the lift mechanism and the rotating mechanism are disposed within a frame below the first housing.
 34. The valve of claim 26 wherein the housing includes at least one opening in a surface substantially perpendicular to the passageway, wherein the at least one opening is configured to serve as a vacuum feed through for a drive mechanism of a substrate transfer mechanism.
 35. The valve of claim 26 wherein the housing includes at least one opening in a surface substantially perpendicular to the passageway, wherein the at least one opening has dimensions which permit the gate to be removed from the valve housing through the at least one opening.
 36. The valve of claim 26 wherein the housing includes a top surface having at least one opening therein to aid visual inspection of the gate while the gate is disposed within the housing.
 37. A substrate processing system comprising: first and second processing chambers each having respective interior regions; a first valve housing disposed between the first and second chambers and adjacent the first chamber, and forming a first substrate passageway to the first chamber; a first gate disposed within the first valve housing, wherein the first gate is movable between a first position in which the first passageway is open and a second position in which the first passageway is sealed; a first actuator mechanism disposed within a first frame and coupled to the first gate for controlling movement of the first gate between the first and second positions; and a second valve housing disposed between the second chamber and the first valve housing, and forming a second substrate passageway to the second chamber; a second gate disposed within the second valve housing, wherein the second gate is movable between a first position in which the second passageway is open and a second position in which the second passageway is sealed; and a second actuator mechanism disposed within a second frame and coupled to the second gate for controlling movement of the second gate between its first and second positions, wherein each actuator mechanism includes: (a) a lift mechanism for causing an associated one of the gates to move between its first position and an intermediate raised position opposite the passageway; and (b) a rotating mechanism having respective first and second positions, wherein movement of the rotating mechanism between its first and second positions causes the associated gate to rotate between its intermediate raised position and its second position.
 38. The system of claim 37 further wherein the respective valve housings and actuator mechanism frames are asymmetrically formed so that the first valve housing partially overlaps the second actuator mechanism frame.
 39. The system of claim 38 wherein the first valve housing includes at least one opening in a surface substantially perpendicular to the passageway, wherein the at least one opening is configured to serve as a vacuum feed through for a drive mechanism of a substrate transfer mechanism.
 40. The system of claim 37 wherein the first valve housing in integrally formed as a single unit with the first chamber, and the second valve housing is integrally formed as a single unit with the second chamber.
 41. The system of claim 37 wherein each lift mechanism includes a lift cylinder and wherein each rotating mechanism includes at least one push cylinder. 